The animal core will be responsible for providing all animals for Projects 2, 3, 4 and 5. This involves ordering young animals in the initial year to supplement our own colony to provide older animals in later months. Old animals will also be purchased from NIA-subsidized colonies as may be needed until subjects of suitable ages can be obtained from our own stock. The main reason for aging our own animals is to monitor and control their exposure to noise by keeping them in acoustically controlled conditions. In addition, we wish to maximize the survival of the aging animals by raising them in specific pathogen-free environments. In that regard, we will work closely with the Medical Center Vivarium staff to monitor the health of our populations. Besides the rearing of the subject populations, the animal core will be primarily responsible for documenting the life history of each animal and the experiments in which it participates. It will also establish timetable for scheduling and delivery of animal subjects to the different projects at the appropriate times.